Honda-SOHC

SOHC.co.uk Forums => CB350/400 => Topic started by: billywingnut on September 11, 2018, 08:15:31 PM

Title: Cylinder one running cooler than other three
Post by: billywingnut on September 11, 2018, 08:15:31 PM

Having restored my bike and done around 300 miles I notice cyl. one runs cooler from cold start, when hot it's difficult to tell. The carbs all had new DS kits fitted and I balanced carbs twice. The valves were lapped and new rings fitted, new plugs and plug tops. bike now has 34000 on it. No smoke and it pulls well. I have done valves to 3 thou for the hot summer. I thought I knew the answers to most things but not so sure now.  Before I start ripping things apart again I would appreciate your views.

Title: Cylinder one running cooler than other three
Post by: petermigreen on September 11, 2018, 08:32:15 PM

As cylinders 1&4 share coils/points probably safe to eliminate those.
New plugs aren’t guaranteed good though. I’d try swapping plug with another cylinder first to eliminate or prove plug In number one is all good. Also double check lead/cap.
Peter


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Title: Re: Cylinder one running cooler than other three
Post by: Nurse Julie on September 11, 2018, 09:17:58 PM

Could it be a case of No 1 cylinder is running at the correct temperature and 2,3 and 4 are running very hot?

Title: Re: Cylinder one running cooler than other three
Post by: Rob62 on September 11, 2018, 09:37:07 PM

Compression test?

Title: Re: Cylinder one running cooler than other three
Post by: Tomb on September 12, 2018, 07:21:57 AM

what he^ said

Title: Re: Cylinder one running cooler than other three
Post by: K2-K6 on September 12, 2018, 09:44:10 AM

To add to the considered list,  you could try warming it and then individually turning the pilot/idle circuit screws to judge if you've got the same response to each carb. 

If you get very different or no change from one carb it would suggest that idle circuit to be impaired and maybe affecting the low response mixture.